28 REVISION OF THE PELYCOSAURIA. 



"The dorsal vertebrae have their sides somewhat contracted ; in one specimen the 

 inferior face is ronuded; in another, which I suppose to belong to a different part of 

 the column, it is longitudinally acute. In this and another dorsal, where the parts 

 are exposed, the floor of the neural canal is interrupted by a deep fissure, which has 

 a triangular shape with apex downward when seen in profile. This is due to the fact 

 that the opposite halves of the centrum are united by the circumferences of the artic- 

 ular cups, which have in profile an X-shape. The diapophysis does not project far 

 beyond the base of the neural arch and is compressed. The caudals are elongate, and 

 resemble, in the forms of the centrum and neural arch, those of Lcrlaps. The neural 

 spines are not preserved, but if present were directed well backwards, bearing the 

 posterior z)'gapoph)-ses, since the arch stands only on the anterior three-fifths of the 

 centrum. Chevron facets are not distinct, but two emarginations on the rim of the 

 posterior face of one of the vertebrae indicate their existence. In other centra even 

 these notches are wanting. The tail was evidently tapering. There is no evidence 

 of the transverse fissures seen in Sphenodon and man}' Lacertilia, nor are there any 

 diapophyses on the caudal vertebra preserved." 



Original description of the homeotype, 1878. Char. Gen., et ccctera: "There is 

 no quadrato-jugal arch, but the zygomatic and postorbital arches are present. The 

 squamosal extremity of the zygomatic arch descends low on the quadrate as in turtles, 

 preventing mobilit)- of the latter. The quadrate is not prominent in the specimen, 

 and appears to ha\-e been a thin bone, as in Edocynodon. The nostril is large and 

 latero-anterior. The symphysis of the mandible is short, and the premaxillary bones 

 appear to be distinct ; they are separated in the specimen by displacement, with the 

 indication that the junction was sutural. The teeth were of different sizes, and the 

 premaxillaries and canines are distinguished from the others by their proportions. 

 All are subround in section, with more or less defined anterior and posterior cutting 

 edges. The premaxillary teeth are larger anteriorly, diminish posteriorly, and are 

 separated by a notched diastema from the large canine. The succeeding teeth are of 

 medium proportions. The roots are sunk in deep alveoli. There is no surface 

 sculpture of the cranial bones, which is the character distinguishing the genus Ecto- 

 cynodon from Clepsydrops. 



" The vertebrae have been described elsewhere, but important additions to our 

 knowledge can now be made. There are mostly small intercentra throughout the 

 dorsal and caudal series, in the latter prolonged into two processes below, constituting 

 the chevron bones. The transverse processes on the dorsal and lumbar vertebrae are 

 undivided, and on some of the dorsals, the ribs articulate with the centrum as well. 

 They are present on the anterior, but wanting on the posterior caudal vertebrae. In 

 adults the neural arch is coossified with the centrum, and on the lumbar and sacral 

 region the neural spines are greatly elevated, indicating the presence of a fin like 

 that of Basilisats. In one of the allied species the diapophyses of the three vertebrae 

 are vertically expanded for the attachment of the ilium, but the centra are not 



coossified. 



"The humerus in this genus is of remarkable character. Its proximal extremity 

 is expanded and regularly convex, with the articular surface at right angles to the 

 sides of the bone, and not developing a head. There is a strong deltoid ridge or tuber- 

 osity, not extending far from the head. The shaft is much contracted, and the distal 

 end is more expanded than the proximal. It is flattened and supports no condyle. 



